Stacking device for flexible workpieces

ABSTRACT

A succession of work pieces, moving along a work table past a sewing machine, are stacked on a rail beyond a transverse discharge edge of the work table by being allowed to depend from that edge between the table and the rail for at least half of their length, the leading end of each workpiece being clamped in position while the trailing end is thrown across the rail so as to be draped symmetrically therearound.

United States Patent [l Nicolay et al. 1 Dec. 5, 1972 [54] STACKING DEVICE FOR FLEXIBLE [5 6] References Cited WORKPIECES UNITED STATES PATENTS [72] Inventors Karl NicPlayi Konrad Ponmeie" 2,151,136 3/1939 Moffit ..271/74 both 3181mm, Germany 1,337,231 4/1920 Jennings ..271/85 [73] Assignee: Durkoppwerke GmbH, Bielefeld, 283,201 8/1883 Campbell ...271/74 Germany 3,097,599 7/1963 Rutishauser ....271/74 Filed; March 1970 Primary Examiner-Joseph Wegbreit No: Attorney-Karl ROSS Related U.S. Application Data S CT [62] Division of Ser. N0. 739,733, June 25, 1968, aban- A succession of Work Pieces, o g along a Work doned, table past a sewing machine, are stacked on a rail beyond a transverse discharge edge of the work table 52] U.S. c1 ..271/85, 271/63 y being allowed to depend from that edge between [51] Int. Cl. ..B65n 29/10 the table and the rail for at least half of their length, [58] the leading end of each workpiece being clamped in Field of Search ..271/74, 85, 63, 68

position while the trailing end is thrown across the rail so as to be draped symmetrically therearound.

, 1 Claim, 3 Drawing Figures PATENTEDUEB 5 I912 SHEEI 1 BF 2 KARL NlCOLAY KONRAD POLLMEIER INVENTOR.

BY gg g,

ATTORNEY P'A'TENTEDBE 1912 3.704.884

SHEET 2 BF 2 I as 84 /5() F l G. 2

2|u/---- KONRAD POLLMEIER KARL NICOLAY INVENTOR.

22 52 m 53 BY ATTORNEY STACKING DEVICE FOR FLEXIBLE WORKPIECES This application is a Division of Application Ser. No. 739,733, filed 25 June 1968 now abandoned.

Our present invention relates to a stacking device for flexible workpieces, in particular for precut fabric sheets of predetermined length.

Means are known for guiding workpieces of flexible sheet material, upon which sewing operations have been performed to a stacking device comprising a linearly or pivotally reciprocating stacking bar or rail transverse to the direction of movement of the workpieces to be stacked, the workpieces being successively draped over this bar. Reference may be made in this connection to US. Pat. Nos. 2,743,925 and 2,874,659.

. Stacking devices of the aforementioned types suffer from the drawback that the entire stack, which may attain a considerable weight, must be carried back and forth during the operation. A further disadvantage of such systems is the limited storage capacity of the stacking bars because of the space required for their oscillating motion. Thus, the bar must be emptied, at relatively short intervals; also, the reciprocation of the stack induces impacts which tend to dislodge the goods from the bar. a t

It is the general object of our present invention to provide simple and reliable means for stacking such flexible workpieces with avoidence of the aforestated disadvantages.

A more specific object of our invention is the provision of a stacking device which can be used with sewing machines equipped with either continuously or intermittently operable feed means for the work.

These objects are realized, pursuant to our invention, by the provision of a stacking device which comprises a generally horizontal work table having a transverse edge for the discharge of a workpiece displaced thereacross, this edge being elevated sufficiently to let at least half the length of the workpiece depend therefrom. A deflector beneath the table, such as a mechanical pusher or an air-blast generator, is operable upon the'arrival of aworkpiece in this dependent position to drape the trailing end of the workpiece about an elongate stacking member, such as a bar or rail, horizontally disposed beyond the discharge edge and below the level thereof, a clamping mechanism being simultaneously effective to hold the leading end of the workpiece substantially immobilized on one side of the stacking member until the trailing end hangs down on the opposite side.

If the workpiece is advanced into its aforedescribed starting position in which at least half of it depends from the discharge edge of the work table, the clamping mechanism may comprise a horizontal arm or the like which, while extending over all or part of the width of the workpiece, is displaceable generally horizontally to urge the workpiece into contact with the stacking member or with a workpiece already positioned thereon. In other instances, the clamp may be a vertically reciprocable gripper which normally occupies an elevated position, in line with the discharge edge, to receive the dependingportion of the workpiece and which is then closed and lowered to draw the remainder of the leading half of the workpiece across this edge preparatorily to actuation of the deflecting mechanism.

These and other features of our invention will become more clearly apparent from, the following detailed description given with reference to the accompanying drawing in which:

FIG. 1 is a partly diagrammatic side-e1evational view of a system for stacking a succession of workpieces, coming from a sewing machine, in accordance with a first embodiment of our invention;

FIG. 2 is a view similar to FIG; 1, illustrating a second embodiment; and

FIG. 3 is another side-elevational view, showing the system of FIG. 2 in an alternate position. I I

In the embodiment of FIG. 1, a work table 1 of a conventional sewing machine 2 is provided with a discharge edge .10 which permits a precut fabric sheet 3 tohang down freely under its own weight after passing beneath the stitch-forming means 2' of the machine. Underneath the edge 10 we provide a clamping member 30, in the shape of a horizontal bar, which normally occupies a retracted position,'shown in full lines, and can be swung toward a stacking rail 20 to assume a clamping position, illustrated in dot-dash lines. The clamping member 30 is attached to the upper end of a reciprocable arm 32 which is pivoted on a horizontal axle 31 secured to a base 22 rigid with table 1. A fluidoperable pressure cylinder 33, having a piston 33' articulated with the necessary play to arm 32 at 34, is mounted on a standard rising from that base. The pressure cylinder 33 is connected to a source of compressed air, not shown, through a valve 71 controlled by a timer 72. Rail 20 is fixedly mounted (e.g. by welding) beyond the edge 10, and below the'level thereof, on an upright 21 also rising from the base 22.

A deflector located underneath the work table 1 composes a horizontal bar 40 carried at right angles on the free end of a piston 41 of, another pressure cylinder 42. The'bar 40 extends parallel to rail 20, above the level thereof, and is normally withdrawn under the table 1 so as to lie forwardly of the depending leading end 4 of the workpiece 3 which has already passed the discharge edge 10. Cylinder 42 is also secured to upright 70 and connected with the same or another source of compressed air, not shown, through a valve 73 also under the control of timer 72.

The clamping and deflecting bars 30, 40 should not become operative until the trailing end of the workpiece 3 has cleared the stitchforming means 2 of the sewing machine 2. Thus, the timer 72 may be triggered by a cloth feeler or other sensing device mounted on the work table 1, or by a conventional thread cutter operating to sever the sewing thread between workpieces successively fed past the needle foot. As illustrated diagrammatically in FIG. 11, the timer is set in operation by a photoelectric sensor shown to comprise a lamp 74 and a photocell 75, the light path therebetween being interrupted when the end 4 of the cloth reaches a predetermined level. In order to allow for variations in the length of a workpiece, the lamp 74 and the photocell 75 may be vertically adjustable with reference to the machine frame 1, 22. Lamp 74 may be laterally offset from the path of swing of clamping device 30, 32 so as not to interfere with the movement of the depending fabric end 4.

We shall now describe the operation of the system shown in FIG. 1.

A workpiece 3, coming from the sewing machine 2, is continuously advanced by conventional feed means and begins to hang down from table 1 after its forward end 4 has passed the discharge edge 10. When this end 4 reaches the level of the photoelectric sensor 74, 75, timer 72 is triggered to open the valve 71 whereby pressure fluid is allowed to flow into cylinder 33 and the bar 30 is swung counterclockwise to clamp the leading end 4 of the workpiece 3 against the rail 20 or against another workpiece already draped around that rail.

Next, the deflector bar 40 is driven to the rear, into its off-normal position shown in dot-dash lines, by the opening of .valve 73 to admit pressure fluid to cylinder 42. Thus, the trailing portion of the workpiece 3, which has been released fromthe sewing machine 2, is thrown over the rail 20 so as to .hang down on both sides thereof in substantially symmetrical fashion. The timer 72 then recloses the valves 71, 73 and operates other valves, not shown, to restore the clamping member 30 and the deflecting member 40 to their normal positions, remote from rail 20.

In FIGS. 2 and 3, wherein elements similar to those of FIG. 1 have been designated by the same reference numerals, we have shown another embodiment of our invention designed for use with a sewing machine (e.g. for buttonholes) which operates only on selected portions of a workpiece after the latter has been properly aligned by a feed mechanism with the stitch-forming means. Thus, in contradistinction to the system of FIG. I, the stacking device of FIGS. 2 and 3 requires special means for positively advancing the workpiece, after completion of the sewing operation, into the correct position for draping around rail 20.

A gripper 80 is mounted on a guide block 86 which is vertically slidable on an upright 87 rising from the base 22. Gripper 80 includes a jaw 81, fixed relatively to block 86, and a movable jaw 82 pivoted on a pin 83. A cylinder 85, connected to a source of pressure fluid through a timer-controlled valve 76, has a piston 85' bearing upon an extension 84 ofjaw 82, the latter being normally held separated from jaw 81 by a compression spring 89.

Block 86 is secured by screws 88 to a traction member 50 here shown as an endless belt guided around upper and lower pulleys 51, 52, the latter pulley being driven by a reversible motor 53 under the control of the timer which has not been illustrated in these Figures.

The two mechanical cloth-handling devices 30, 40 of FIG. 1 have been replaced in this embodiment by a pair of air nozzles 60 and 90 provided with orifices 61, 91 and timer-controlled valves 63, 93, respectively. Each of these nozzles may, of course, form part of a bank of such nozzles extending across the width of cloth 3.

The operation of the system of FIGS. 2 and 3 will now be described.

After the machine 2 has completed its last sewing operation on the workpiece 3, the latter is released in a position in which its end 4 overhangs the edge to a certain extent so as to enter the open jaws of gripper 80 at the upper limit of its vertical stroke (dot-dash lines, FIG. 2). The timer, responding to the programmer for the sewing machine, then opens the valve 76 so that clamp jaw 82 snaps shut (full lines), whereupon motor 53 is started to move the block 86 to its bottom position shown in FIG. 3. Toward the end of the descent of gripper 80, valve 93 is opened to generate an air blast 92 from nozzle 90 which deflects the trailing end 4 of workpiece 3 around the rail 20. At the same time, or slightly thereafter, valve 76 is reclosed and cylinder is vented to let the spring 89 reopen the gripper jaws 81, 82 so as to release the workpiece as illustrated in FIG. 3. With nozzle 60 likewise operated at this instant to emit an air blast 62, as seen in FIG. 3, the leading end of the workpiece is dislodged from the open jaws so as to come to hang down freely from support member 20. Subsequently, motor 53 is driven in the reverse direction to restore the elevated gripper position of FIG. 2. i I

The stacking rail 20, which is stationary during the operations described above, may be replaced by other elongate members and may be mounted on a trolley for removal to another location after a sufficient number of workpieces have been accumulated thereon. Naturally, the mechanical and pneumatic clamping and deflecting devices of the two illustrated embodiments may be interchanged, and the clamping bar 30 of FIG. 1 could be made linearly translatable (rather than swingable) in the manner illustrated for the deflecting bar 40. Also, photoelectric sensors or mechanical feelers (i.e., sensitive switches) may be used in the embodiment of FIGS. 2 and 3 to start the timer in the workpiece position illustrated in FIG. 2. The systems described above, moreover, may be employed in connection with machinery other than sewing machines.

These and other modifications, readily apparent to persons skilled in the art, are intended to be embraced within the spirit and scope of our invention as defined in the appended claims.

We claim:

1. A system for the stacking of a succession of workpieces arriving over a predetermined path, comprising:

a substantially horizontal support for said workpieces, said support being provided with a transverse discharge. edge at the end of said path;

a gripper with normally open jaws disposed beneath said support in alignment with said edge for engaging a leading end of a workpiece hanging down from said edge;

drive means for vertically reciprocating said gripper between an upper position close to said support and a lower position remote therefrom;

operating means synchronized with said drive means for closing said jaws around said leading end in said upper position and for releasing said leading end in said lower position upon downward entrainment of an engaged workpiece;

a substantially horizontal elongate stacking member extending parallel to said edge below the level of said support and above the level of said lower position;

first nozzle means between the levels of said stacking member and said support operative upon a descent of said gripper to said lower position for training a first air blast upon a trailing end of said workpiece, thereby throwing said trailing end across said stacking member; and

second nozzle means below the level of said support and above the level of said lower position operative upon the reopening of said jaws for training a W E TEFMATE M QQRR N" enoegeee Dated 5 D'eeember' 1972 Patent No.'

*mvegwflS) Karl LNICOLAY et a1 It: is certifiedthat error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

115 the .hading, column 1 after line and befqre "line-537 ead; I I ---Eo z"e i gn ApPlieetionData, Germany; l30 dime 1967; l i I 5 B53488: arm @ermafiy, 20 September 1967, p54l62 slgnedw; and sealed this 10th day of July 1973 {S ALJ' Attest EDWARD M.PL T :HER', R;= R en e T egjtmeyer T V Attesting Officer- Acting Commissioner" Q'f Patents 

1. A system for the stacking of a succession of workpieces arriving over a predetermined path, comprising: a substantially horizontal support for said workpieces, said support being provided with a transverse discharge edge at the end of said path; a gripper with normally open jaws disposed beneath said support in alignment with said edge for engaging a leading end of a workpiece hanging down from said edge; drive means for vertically reciprocating said gripper between an upper position close to said support and a lower position remote therefrom; operating means synchronized with said drive means for closing said jaws around said leading end in said upper position and for releasing said leading end in said lower position upon downward entrainment of an engaged workpiece; a substantially horizontal elongate stacking member extending parallel to said edge below the level of said support and above the level of said lower position; first nozzle means between the levels of said stacking member and said support operative upon a descent of said gripper to said lower position for training a first air blast upon a trailing end of said workpiece, thereby throwing said trailing end across said stacking member; and second nozzle means below the level of said support and above the level of said lower position operative upon the reopening of said jaws for training a second air blast upon the released trailing end of said workpiece to dislodge same from said gripper. 